Trunk Priorty feature would be cool

[wlmr]

No, actually they are normally in increments of 32, just divisible by 16. If you look at a typical Moto Type II system you will see they start at TG 16 and the next one is 48, then 80, 112, 144, etc.

Most everyone already knows this but just as a reminder, P25 9600 baud systems don't have this restriction/limitation. Every number is available for talkgroup use (within the 80000001 to 80065534 range). This also makes them available for being a priority-scan flagged talkgroup.

 

[WayneH]

Most everyone already knows this but just as a reminder, P25 9600 baud systems don't have this restriction/limitation. Every number is available for talkgroup use (within the 80000001 to 80065534 range). This also makes them available for being a priority-scan flagged talkgroup.

Completely different circumstances. Since everything is digital with P25 trunking you have a different way to convey the priority-marked TGs.

 

[loumaag]

...Since everything is digital with P25 trunking you have a different way to convey the priority-marked TGs.

Wayne, in reference to this, how is it handled in Motorola Type II systems that are 100% P25 CAI? I know that the ability still exists from when I was in South Dakota as the system was set up for priority scanning but since there was no analog (and hence no slow speed data) is this information passed both on the 3600 BPS CCh and in the digital streams during TG activity?

 

[wlmr]

Wayne, in reference to this, how is it handled in Motorola Type II systems that are 100% P25 CAI? I know that the ability still exists from when I was in South Dakota as the system was set up for priority scanning but since there was no analog (and hence no slow speed data) is this information passed both on the 3600 BPS CCh and in the digital streams during TG activity?

I think in this respect that the 3600 and 9600 P25 systems are the same.

The control channel in either instance carries all the info about what talkgroups are assigned what voice frequency. Kinda doubt the control channel indicates any difference between priority or non-priority talkgroups. For sure on the 9600 baud systems the priority talkgroups are listed at a very slow rate that is included within the P25 digital signal that the receiving radio hears on the assigned and in use "voice" frequency. (Only way that a half-duplex radio can be listening to one thing and know to go listen elsewhere.)
Unlike the control channel, the voice channel priority talkgroup scroll is really slow. Takes an eternity considering conversations may be over in just a few seconds.

As I understand analog only systems, one of the bits between each 16 spaced apart talkgroup IDs signifies it's a priority talkgroup. Am I right on this?

Tough part for scanning (whatever type system you're monitoring) is that what you want as priority may not match what has been assigned as priority in the system. I need to remember to look for info on whether a site that doesn't have a radio affiliated that is on a priority talkgoup will even include that talkgroup in the slow data info on the voice frequencies.

 

[WayneH]

I think in this respect that the 3600 and 9600 P25 systems are the same.

On an ASTRO25 voice channel regardless of the system type the data being passed is the same. The TG IDs are the only thing sent. When a radio sees a desired TG it switches back to the CC and gets the late entry announcement then switches to that channel. You don't want to add too many TGs for priority scan because of what you mentioned (the time it takes 'round trip').

Neither the CC or VC indicate any type of priority level. The only indication of priority is the existence within the priority scan stream.

I need to remember to look for info on whether a site that doesn't have a radio affiliated that is on a priority talkgoup will even include that talkgroup in the slow data info on the voice frequencies.

Huh? The low-speed (or CAI data) only lists active priority TGs at the current site. So affiliations are irrelevant. Am I misinterpreting what you're saying?

 

[loumaag]

On an ASTRO25 voice channel regardless of the system type the data being passed is the same. The TG IDs are the only thing sent. When a radio sees a desired TG it switches back to the CC and gets the late entry announcement then switches to that channel. You don't want to add too many TGs for priority scan because of what you mentioned (the time it takes 'round trip').

Neither the CC or VC indicate any type of priority level. The only indication of priority is the existence within the priority scan stream.

Thanks for the info Wayne.

 

[wlmr]

Huh? The low-speed (or CAI data) only lists active priority TGs at the current site. So affiliations are irrelevant. Am I misinterpreting what you're saying?

Probably was a better way of my saying or asking that. <grin>

What I was asking was -
In a multiple zone/site system where a priority talkgroup is actively chattering, will the voice channel data exist for sites where no radios are affiliated on that talkgroup - or - will it only announce the existence of the priority talkgroup at site(s) where radios are using that talkgroup.

In other words, how smart is the system in this regard?

 

[WayneH]

will it only announce the existence of the priority talkgroup at site(s) where radios are using that talkgroup.

The voice channels will only announce activity for the current site. Networked systems aren't any different. So if the site is broadcasting a talkgroup then someone has affiliated to it (or it's configured to always broadcast).